One of the problems with using poison is that rats and mice reproduce so quickly that they gain immunity to the poison very quickly. Most modern rat poison is an anti coagulant similar to warfarin sodium (Coumadin) some folks take for blot clots. That being said, when I had rats in my attic in Dallas I first went to a DIY pest control place I found on google and the recommended using 2 different types of bait/poison. The next thing the guys told me is that its very important to clean up the area where you find droppings and remove any and all sources of food, that way they will go after the bait. I would do a bit of research from credible sources first then decide which approach is best, traps, bait, or maybe a combination of both.